1. Field of the Invention
Exemplary embodiments of the present invention relate to a method of measuring a three-dimensional shape. More particularly, a method of measuring a three-dimensional shape capable of measuring a three-dimensional shape of a board by realigning an inspection area of the board using feature information extracted from CAD information of a bare board or feature information extracted from learning of the bare board.
2. Discussion of the Background
A conventional method of measuring a three-dimensional shape is explained in schematically as follows.
In order to measure a three-dimensional shape of a printed circuit board (PCB) (hereinafter, referred to as board, wherein the board includes solder formed thereon), the conventional method of measuring three-dimensional shape includes a two-dimensional inspection and a three-dimensional inspection.
In the two-dimensional inspection, two-dimensional lighting is illuminated onto a board, and a two-dimensional image reflected from the board is photographed and inspected by using a camera. In the three-dimensional inspection, a projector generates a pattern light and illuminates the pattern light onto a board, and a reflected pattern image is photographed and inspected by using a camera.
In the three-dimensional inspection, in case that phase information is obtained by using N-bucket algorithm, a grating of a projector is transferred at regular intervals by N-times to obtain N pattern images. After the N pattern images are obtained, phase information is obtained by using N-bucket algorithm, and height information of an inspection target in an inspection area of a board is produced by using the obtained phase information to thereby measure the three-dimensional shape.
When the phase information is obtained by using the N-bucket algorithm to measure the three-dimensional shape of the board, the board may be warped or contracted in a process of forming solder on the board or for other reasons.
When the board is warped or contracted, the defined inspection area is distorted. When the defined inspection area is distorted, the conventional method of measuring a three-dimensional shape may not detect the distortion of the inspection area, and thus the conventional method may not precisely measure a three-dimensional shape.